Here i am asking basic question related to analog calibration.
I have MSP430g2553 Series .
I have Analog sensor which take 5 v as supply and output varies 2mv per degree. 2.5v means 0 degree for reference. varies up to +72deg to-72 deg .
Since MSP can read 2.6v max in analog pin. How to calibrate it software to match sensor voltage.

You need to use a resistive voltage divider to bring the voltages output by the sensor down to the range that the analog input can accommodate. Two 10K ohm resistors should work to divide by two, but read the MSP430 data sheet to discover what the maximum source impedance on an analog input can be. Keep in mind that the divider will reduce the voltage swing to 1 mV per degree.